From 564e53cdd4d6fc8b611d59c2c19af42864e6ece4 Mon Sep 17 00:00:00 2001
From: Adrien Hopkins <adrien.p.hopkins@gmail.com>
Date: Mon, 7 Aug 2023 16:34:47 -0500
Subject: Add totative ratio and factor score to program

---
 factors/totative.go | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)
 create mode 100644 factors/totative.go

(limited to 'factors/totative.go')

diff --git a/factors/totative.go b/factors/totative.go
new file mode 100644
index 0000000..558f0f0
--- /dev/null
+++ b/factors/totative.go
@@ -0,0 +1,17 @@
+package factors
+
+// TotativeRatio calculates the fraction of numbers less than n that
+// are totatives of n (share no factors with n)
+func TotativeRatio(n uint) float64 {
+	if n == 0 {
+		panic("0 has no totative ratio!")
+	}
+
+	primeFactorization := PrimeFactorize(n)
+
+	totativeRatio := 1.0
+	for p := range primeFactorization.exponents {
+		totativeRatio *= float64(p - 1) / float64(p)
+	}
+	return totativeRatio
+}
-- 
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